title: Elevational patterns of genetic variation in the cosmopolitan moss Bryum argenteum (Bryaceae).
abstract: OBJECTIVE
  The Baas Becking tenet posits that 'everything is everywhere, but the environment selects' to explain cosmopolitan distributions in highly vagile taxa. Bryophyte species show wider distributions than vascular plants and include examples of truly cosmopolitan ranges, which have been interpreted as a result of high dispersal capacities and ecological plasticity. In the current study, we documented patterns of genetic structure and diversity in the cosmopolitan moss Bryum argenteum along an elevational gradient to determine if genetic diversity and structure is homogenized by intense migrations in the lack of ecological differentiation. •
  
  
  METHODS
  60 specimens were collected in the Sierra Nevada Mountains (Spain) between 100 and 2870 m and sequenced for ITS and rps4. Comparative analyses, genetic diversity estimators, and Mantel's tests were employed to determine the relationship between genetic variation, elevation, and geographic distance and to look for signs of demographic shifts. •
  
  
  RESULTS
  Genetic diversity peaked above 1900 m and no signs of demographic shifts were detected at any elevation. There was a strong phylogenetic component in elevational variation. Genetic variation was significantly correlated with elevation, but not with geographic distance. •
  
  
  CONCLUSIONS
  The results point to the long-term persistence of Bryum argenteum in a range that was glaciated during the Late Pleistocene. Evidence for an environmentally driven pattern of genetic differentiation suggests adaptive divergence. This supports the Baas Becking tenet and indicates that ecological specialization might play a key role in explaining patterns of genetic structure in cosmopolitan mosses.
authors.affiliation: Departamento de Biología Vegetal (Botánica), Facultad de Biología, Universidad de Murcia, Campus de Espinardo 30100 Murcia, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Pisa
authors.forename: Olaf
authors.initials: O
authors.lastname: Werner
authors.forename: Alain
authors.initials: A
authors.lastname: Vanderpoorten
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Magdy
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Ros
mesh_terms: D000531:Altitude; D001483:Base Sequence; D044002:Bryophyta / Q000235:genetics*; D021901:DNA, Intergenic / Q000235:genetics; D014644:Genetic Variation; D006238:Haploidy; D010802:Phylogeny
chemical_list: D021901:DNA, Intergenic
keywords: Baas Becking tenet; Bryum argenteum; adaptive divergence; bryophytes; cosmopolitan species; elevational gradients; genetic diversity; mountains